Roller track device for moving a load in a substantially horizontal plane

ABSTRACT

The invention concerns a roller track device based on simple kinematics without energy input, enabling reduction of the number of parts, of production cost of the assembly and of its space requirement, easy maintenance, and designed for being fitted on new handling apparatuses as well as for retrofitting. The roller track device ( 100 ) comprises a rail ( 310 ) bearing the static load, a guard rail ( 210 ) housed in the rail ( 310 ) and wherein are mounted rolling members ( 230 ) bearing the moving load. The guard rail ( 210 ) is coupled to a pivoting lever ( 410 ) co-operating with a lift bar ( 450 ) directly mounted on a machine ( 20 ) for moving the guard rail ( 210 ) relative to the rail ( 310 ) between a low position and a high position, wherein the load is supported either by the rail ( 310 ) or by the guard rail ( 210 ). The pivoting lever ( 410 ) transforms the vertical upward force exerted by the lift bar ( 450 ) into a horizontal force on the guard rail ( 210 ) to move it in horizontal translation (Th). The rail ( 310 ) comprises inclined ramps ( 331 ) co-operating with the rolling members ( 230 ) to move it in vertical translation (Tv) simultaneously with its horizontal movement (Th). The invention is useful for transferring heavy loads in a substantially horizontal plane between a fork handling apparatus and a machine such as a machine-tool, a press, and injection machine and the like.

The present invention concerns a roller track device for moving a loadin a substantially horizontal plane between a load handling apparatusand a machine, said device being used to equip the forks on saidhandling apparatus and comprising at least one rail defining at leastone plane contact surface capable of supporting said load when it isstatic, said rail being hollow, substantially horizontal, and having alongitudinal opening, at least one counter-rail housed within said railwithin which roller devices are attached opposite said longitudinalopening, said roller elements being contained in a plane that isgenerally parallel to said surface and being capable of supporting saidload when it is moving, at least one of the structures being associatedwith actuation means so to be movable relative to the other between atleast a lower position and an upper position, in which positions theload is supported either by the rail or by the counter-rail, saidactuation means displacing the structure known as the movable structurein at least horizontal translation, and lifting means located betweenthe two structures so as to generate vertical displacement of thestructure known as the movable structure simultaneous with itshorizontal displacement. The present invention also concerns a handlingdevice with forks that is equipped with such a roller device.

In industry, load handling platforms such as, for example, elevator carsand stacking equipment are currently used to handle heavy loads. Theseheavy loads might consist of tools for machine tools, presses used tocut or stamp metal, or molds or forms used in the injection of syntheticmaterial, etc. Generally, loads of less than two tons are transported onload handling platforms, while loads from two to ten tons aretransported using fork apparatuses. Loads of over ten tons aretransported by cranes.

To facilitate the transfer of loads in the horizontal plane from thehandling platform to the machine tool or vice versa, handling equipmentnow in use is provided with a roller device integral with the forks,designed to support the load and displace it without friction on thefree roller devices. This handling equipment may also be provided witharticulated arms designed to push or pull the load. The roller devicegenerally comprises a “roller support structure” surmounted by a “loadsupport structure.” The function of the load support structure is tosupport the load while the handling apparatus moves, whereas thefunction of the roller support structure is to support it withoutfriction in order to effect the transfer. Passing the load from onestructure to the other and vice versa is accomplished through thedisplacement of one structure relative to the other so that the rollerdevices on the roller-support structure can be retracted or extendedrelative to the load support structure, said relative displacement beingcontrolled by means of manual or automatic actuators.

In load handling devices using forks, this relative movement isgenerally controlled automatically either by a block provided on themachine tool and cooperating with said movable structure when the forksare attached, or by a cylinder integrated within the handling apparatus.

In Publication DE-A-36 20 964 displacement of the structure called themovable structure is generated by a stop when the forks are attached tothe machine tool, which causes the roller support structure to rise bymaking it pivot on an axle located in the tablet of the load handlingapparatus. This is not a satisfactory solution because it requires abroad amplitude of movement, which increases the time required totransfer the load and necessitates use of large fork due to thisamplitude. Moreover, the load is not uniformly distributed and there isno guaranty of simultaneous movement between the roller supportstructures, leading to premature wear and deterioration of the rollerdevice. In addition, this system cannot be adapted to equip loadhandling apparatuses already in use.

In Publications U.S. Pat. No. 3,243,029, U.S. Pat. No. 4,930,612 andU.S. Pat. No. 5,915,515, displacement of the structure called themovable structure is accomplished by a cylinder that raises the rollersupport structure through the intermediary of inclined ramp systems orbearings. These solutions are unsatisfactory as well, since they requirea specific external energy source for supplying the cylinder orcylinders. These approaches are complex, expensive, and require a lot ofspace. Moreover, their design does not facilitate cleaning andmaintenance of the roller devices, since the roller support device isdifficult to disassemble. Finally, they are not suitable forretrofitting load handling apparatuses already in use.

The present invention proposes overcoming these disadvantages with aroller device based on simple kinematics without any outside energysource which limits the number of pieces, reduces both the cost andspace requirements for the unit, facilitates maintenance and cleaning,and which is suitable for both new apparatus and retrofitting existingones.

To achieve this, the invention concerns a roller device of the typeindicated in the preamble characterized in that the actuation meanscomprises at least one block designed to be installed on said machineand at least one actuator located between the two structures whichcooperates with said block so as to transform a vertical force exertedby said block on said actuator into a horizontal force exerted by saidactuator onto said structure called the movable structure, displacing itin horizontal translation when the forks of the load handling devicesare attached to said machine.

In a preferred embodiment the lifting means comprises inclined rampsintegral with said rail which cooperate with said roller elements onsaid counter-rail. These inclined ramps define at least a first zonewhich allows at least the tops of the roller elements to project, asecond zone designed to cover the roller elements, and an intermediatezone designed to form, in combination with the roller elements, thelifting ramps. Each roller element advantageously comprises at least oneroller designed to support the load in position for motion, said rollerbeing attached to a generally horizontal axle between two rollers ofsmaller diameter, with the rollers being in contact with the inclinedramps.

In a variation the lifting means may comprise articulated bearingshaving one extremity connected to said rail and other extremityconnected to said counter-rail.

Said actuator may be chosen from the group comprising at least apivoting lever, a ball and socket, a rotating device, or a cylinder.

Preferably the rail is fixed and the counter-rail supporting the rollerelements is movable and cooperates with said actuator, the purpose ofsaid actuator being to displace the counter-rail from its lower positionto its upper position when it is in contact with the block and to allowthe counter-rail to descend by gravity when it is no longer in contactwith the block.

In a first variation, the actuator comprises at least one pivoting leverattached to the rail by an axle oriented in a generally perpendicular tothe direction of horizontal displacement of the counter-rail, saidpivoting lever comprising at least two contact zones located on eitherside of the axle, one of which is in contact with the counter-rail andthe other of which cooperates with said block. This pivoting levercomprises at least one roller located between the two contact zones anddesigned to supplement the roller elements on the counter-rail when itis in the upper position.

In a second variation the actuator comprises at least one pivoting leverattached to said counter-rail by an axle oriented generallyperpendicular to the direction of horizontal displacement of thecounter-rail, said pivoting lever comprising at least two contact zones,one of which is in contact with the rail and the other of whichcooperates with said block. One of the contact zones preferablyconstitutes a ramp capable of cooperating with a rotating elementintegral with said rail.

In a third variation, the actuator comprises at least one rotatingelement attached to said counter-rail by an axle oriented generallyperpendicular to the direction of horizontal displacement of thecounter-rail, said rotating element being designed to move along aninclined ramp integral with said block, said rail being guided invertical translation within said block by a tenon-slide system.

In a fourth variation the actuator comprises at least one ball andsocket consisting of at least one contact zone located at theintersection of two articulated lever arms and respectively connected tosaid rail and said counter-rail along two axles generally perpendicularto the direction of horizontal displacement of said counter-rail, withthe contact zone being designed to cooperate with said block. Thecontact zones advantageously consist of rotating elements.

In a fifth embodiment the actuator comprises at least one doublecylinder, a first piston of which cooperates with said counter-rail andis oriented generally perpendicular to the direction of its horizontaldisplacement, with the second piston cooperating with said block andoriented generally perpendicular to said first piston. The second pistonis preferably associated with a recall device. The piston chambers maybe separate and connected by at least one conduit housed within therail.

In a sixth embodiment the actuator comprises at least one rotatingelement attached to the rail by an axle oriented generally perpendicularto the direction of horizontal displacement of the counter-rail andguided translationally within the rail by grooves, said rotating elementcooperating with two ramps that are provided on the rail and thecounter-rail, respectively, at least one of the ramps being inclined.This rotating element comprises at least three coaxial rollers ofdifferent diameters, at least two of which are movable in relation toeach other, said rollers cooperating respectively with the ramp integralwith the rail, the ramp integral with the counter-rail, and the block.

The block is preferably selected from among at least a tie rod which canreceive the front extremity of said forks and a machine table, saidblock being at least partially shaped to be compatible with theactuator.

For the same purpose, the invention concerns a load handling apparatuswith forks of the type indicated in the preamble characterized in thatit comprises at least one roller device as defined above.

The advantages of the present invention will be more apparent from thefollowing description of several embodiments cited by way ofnon-limiting examples, with reference to the attached drawings, wherein:

FIG. 1 is a perspective of a roller device according to the invention inthe shape of a fork;

FIG. 2 is a partial perspective of the device of FIG. 1;

FIG. 3 is a functional schema of the device of FIG. 1;

FIGS. 4A and 4B are partial side views of the device of FIG. 1, shownrespectively in the extended and retracted positions;

FIG. 5 is a functional schema of a first variation of the device of theinvention;

FIGS. 6A and 6B and partial side views of the device corresponding toFIG. 5 shown respectively in the retracted and extended positions;

FIGS. 7A, 7B and 7C are schematic views of a second variation of thedevice according to the invention, respectively showing a side view inthe retracted position, a top view and a side view in the extendedposition;

FIGS. 8A and 8B are schematic views of a third variation of the deviceof the invention shown respectively in retracted and extended positions;

FIGS. 9A and 9B are views similar to FIGS. 8A and 8B with other liftingmeans;

FIGS. 10A, 10B and 11A, 11B are schematic views of a fourth and fifthvariation of the device of the invention shown respectively in theretracted positions and extended; and

FIGS. 12A, 12B, 13A and 13B are schematic views of a sixth and seventhvariation of the invention shown respectively in the retracted andextended positions.

With reference to FIGS. 1 through 4 roller device 100 according to theinvention is fork-shaped and designed to equip a conventional loadhandling device with two parallel forks (not shown). It performs twofunctions: static support with friction of very heavy loads 1 weighingup to about 10 tons while the load handling apparatus is moving, anddynamic support of these loads 1 without friction while they are beingtransferred in a plane A parallel to the forks to or from a machine 20which may be a machine tool, a press, an injection machine, or any otherfixed or movable plane surface.

This roller device 100 comprises a roller support structure 200comprising roller elements 230 surmounted by a load support structure300 having a plane contact surface S provided with an opening 320 whichallows at least the tops of the roller devices 230 to be visible. Inthis embodiment, and as shown schematically by FIG. 3, roller supportstructure 200 is movable, in relation to load support structure 300which is fixed, between two positions, at least one of which is stable:a lower position in which it retracts roller devices 230, with load 1being in plane contact on surface S of load support structure 300, andan upper position in which it releases the tops of roller devices 230,with load 1 being either in linear contact or contact at some points onroller elements 230. Obviously the reverse configuration is alsopossible, that is, having the load support structure 300 movablerelative to roller support structure 200.

Roller support structure 200 is associated with actuation means 400which displace it in horizontal translation Th along a course Ch andwith lifting means 500 which displace it in vertical translation Tv on acourse Cv simultaneously with horizontal displacement Th, with course Cvbeing shorter than course Ch. The originality of roller device 100 ofthe invention resides in the fact that the actuating means 400 ismechanical and automatic, integrated within roller device 100, occupiesonly a small space, and does not require any energy input. The otheroriginality resides in the lifting means 500 which, rather thanconsisting of supplemental expensive and complicated mechanisms, isdirectly integrated within load support structure 300 and roller supportstructure 200. It is the specific result of moving contact betweenpieces 330, 240 respectively provided on load support structure 300 androller support structure 200, said pieces 330, 240 being specificallyshaped to form a lifting ramp as explained below.

In the example shown, load support structure 300 consists of a hollow,U-shaped rail 310 for use in the horizontal position defining alongitudinal opening 320 in the upper portion and an interior housingreceiving roller support structure 200. Said rail 310 comprises at itsrear extremity a vertical support 340 forming a fork 10, said supportbeing equipped with jaws 341 allowing said fork 10 to be attached to thesame place and in the same position as the existing forks on a standardload handling device. At its front extremity, said rail 310 comprises alower notch 350 capable of engaging with a tie rod on a machine 20, forexample. Inside rail 310 blocks 330 with inclined ramps 331 areattached, each block 330 comprising two parallel inclined ramps 331.These inclined ramps 331 define at least one first zone 331 a whichallows at least the tops of roller elements 230 to project, a secondzone 331 b for covering roller elements 230, and an intermediate zone331 c which forms, in combination with roller elements 230, the liftingmeans 500.

The roller support structure 200 constitutes a counter-rail 210 openfrom side to side and with dimensions that are complementary to those ofthe interior housing in rail 310 so as to be freely movable within saidrail 310 in horizontal translation Th and in vertical translation Tv.Said counter rail 210 is guided within rail 310 by their respectivelateral sides. It comprises a plurality of rollers 230 aligned along itsmedian axle in a plane parallel to plane contact surface S of rail 310,said rollers 230 being essentially cylindrical and constituting theroller elements. Each roller 230 is freely attached to a transverse axle220 integral with counter-rail 210. Each transverse axle 220 alsosupports two rollers 240 located on either side of roller 230, having asmaller diameter than roller 230 and positioned opposite and in contactwith ramps 331 on a block 330.

Roller support structure 200 is associated with an actuation means 400which, in the example shown, is mechanical and automatic, and comprisesa block consisting of the tie rod 450 attached to machine 20 and anactuator in the form of a pivoting lever 410 integral with roller device100 and cooperating with said block. The tie rod may be attached tomachine 20 with clamps 451 or any other appropriate means. Pivotinglever 410 is generally triangular with three tips and located in frontof counter-rail 210 in the area of the front extremity of rail 310. Thispivoting lever 410 is attached to an axle 420 integral with rail 310 andperpendicular to direction Th. It is designed to transform a verticalforce exerted by tie rod 450 when forks 10 are attached to machine 20into a horizontal force capable of displacing counter-rail 210 inhorizontal translation. Therefore, the force transmitted by thispivoting lever 410 to counter rail 210 is generally proportionate to thesize of load 1. Said pivoting lever 410 comprises three distinct contactzones forming the three tips of the triangle and constituting rollerelements: a roller 430 located opposite lower notch 350 on rail 310 anddisposed to contact tie rod 450, a roller 440 in moving contact with thefront extremity of counter-rail 210, and a roller 230 disposed tocomplement roller elements 230 on roller support structure 200.Obviously the actuator may consist of any other equivalent means suchas, for example, a cylinder (cf. FIGS. 10 and 11), a nut and bolt, aball and socket (cf. FIGS. 8 and 9), a simplified lever (cf. FIGS. 5 and6), a roller element associated with an inclined ramp (cf. FIG. 7), etc.

FIGS. 4A and 4B illustrate the operation of this pivoting lever 410. InFIG. 4B pivoting lever 410 is at rest, which corresponds to counter-rail20 being in the lowered position in which rollers 230 are retractedinside rail 310. This lowered position is stable. In FIG. 4A pivotinglever 410 is actuated by tie rod 450 added to machine 20 while forks 10descend as the load handling device attaches to machine 20. Tie rod 450exerts on pivoting lever 410 through roller 430 an upward vertical forcecausing it to rotate in a counterclockwise direction at an angle ofabout 45°, moving roller 230 on lever 410 into the extension of theother rollers 230 and pushing counter-rail 210 in horizontal translationTh, said counter-rail simultaneously effecting vertical translation Tvby virtue of the displacement of rollers 240 on inclined ramps 331.Counter-rail 210 is moved to the upper position in which rollers 230project above surface S of rail 310. This upper position is not stablesince when forks 10 are disengaged from tie rod 450, counter-rail 210descends inclined ramps 331 due to gravity and returns to the lowerposition, simultaneously returning pivoting lever 410 to its restingposition (cf. FIG. 4B).

FIGS. 5 and 6 illustrate a roller device 110 similar to the precedingone with only the actuation means 400′ being different. Actuation means400′ comprises an upright pivoting lever 410′ with two extremitiescooperating with a mechanical block consisting of table 20′ of machine20. This pivoting lever 410′ is attached at one end to an axle 420′integral with counter-rail 210 and oriented in a generally perpendiculardirection to the direction of horizontal displacement Th of saidcounter-rail 210. As before, it is designed to transform the verticalforce exerted directly by table 20′ of machine 20 when forks 10 areattached into a horizontal force capable of displacing counter-rail 210in horizontal translation Th. This pivoting lever 410′ comprises twocontact areas 430′, 440′. Contact area 430′ is located at the freeextremity of pivoting lever 410′ and enters into contact with table 20′of machine 20 when forks 10 become attached to tie rod 450′. Contactzone 440′ consists of a ramp extending between the two extremities ofpivoting lever 410′ in a slight curve and capable of cooperating with arotating element 441′ integral with rail 310 and attached to theextremity of support arm 442′.

FIGS. 6A and 6B illustrate the operation of this pivoting lever 410′. InFIG. 6A the pivoting lever 410′ is at rest, corresponding tocounter-rail 210 being in the lower position in which rollers 230 areretracted inside rail 310. This lower position is stable. In FIG. 6Bpivoting lever 410′ is actuated by table 20′ on machine 20 whichtransmits an upward vertical force, causing it to rotate clockwise at anangle of about 30°, with ramp 440′ being displaced relative to fixedrotating element 441′ and generating the displacement of counter-rail210 in horizontal translation Th. The latter simultaneously effectsvertical translation Tv due to the displacement of rollers 240 alonginclined ramps 331. Counter-rail 210 is moved to the upper position inwhich rollers 230 project above surface S of rail 310. This upperposition is not stable because when forks 10 are disengaged from machine20, counter-rail 210 descends inclined ramps 331 due to gravity,returning to the lower position, and returning pivoting lever 410′ toits resting position (cf. FIG. 6B).

FIGS. 7A through 7C illustrate a third roller device 120 wherein theactuation means 600 comprises an actuator in the form of a moving device610 integral with counter-rail 210 and associated with a block formed ofan inclined ramp 620 provided in a tie rod 650 added to machine 20.Moving device 610 may consist, for example, of a roller attached to anaxle at the front extremity of counter-rail 210 and inclined ramp 620 issituated between two lateral sides of tie rod 650. These lateral sidescomprise the parallel and vertical slides 640 which receive tenons 630provided on either side of the front extremity of rail 310 to ensurethat forks 10 are mechanically attached to machine 20.

FIGS. 7A and 7C illustrate the operation of this actuation means 600. InFIG. 7A roller device 120 is at rest, corresponding to counter-rail 210being in the lower position wherein rollers 230 are retracted insiderail 310. This lower position is stable. In FIG. 7C, roller 610 movesalong inclined ramp 620 while forks 10 descend to attach the loadhandling device to machine 20. The vertical force exerted by tie rod 650is transformed into horizontal force against counter-rail 210 because ofthe combination of inclined ramp 620 with roller 610. Counter-rail 210effects, simultaneously with its horizontal translation Th, verticaltranslation Tv due to the displacement of rollers 240 along inclinedramps 331. Counter-rail 210 is moved to the upper position in whichrollers 230 project above surface S of rail 310. This upper position isnot stable because when forks 10 are disengaged from machine 20 towardthe top, rolling element 610 again travels up inclined ramp 620,allowing counter-rail 210 to descend inclined ramps 331 due to gravityand return to the lower position (cf. FIG. 7A).

FIGS. 8A and 8B are schematic representations of a fourth roller device130 in which the actuation means 700 comprises an actuator in the formof a ball and socket 710 integral with roller device 130 and associatedwith a block formed of a tie rod 750 added to machine 20. Ball andsocket joint 710 comprises a rolling element 720 attached to theintersection of two articulated lever arms 730. The extremities of theselever arms 730 are respectively attached to rail 310 and to counter-rail210 by an articulation 740. In FIG. 8A ball and socket 710 is at rest,corresponding to counter-rail 210 being in the lower position in whichrollers 230 are retracted inside rail 310. This lower position isstable. In FIG. 8B ball and socket 710 is actuated by tie rod 750 whichexerts an upward vertical force on rolling element 720 as forks 10descend to attach the load handling device to machine 20. This upwardvertical force is transformed into horizontal force against counter-rail210 due to lever arms 730 and articulations 740. Counter-rail 210effects simultaneously with its horizontal translation Th, verticaltranslation Tv due to the displacement of rollers 240 on inclined ramps331. Counter-rail 210 is moved to the upper position in which rollers230 project above surface S of rail 310. This upper position is notstable because when forks 10 are disengaged from machine 20,counter-rail 210 descends include ramps 331 due to gravity to return tothe lower position and simultaneously return ball and socket 710 to itsresting position (cf. FIG. 8A).

FIGS. 9A and 9B are schematic representations of a fifth roller device140 using the same actuations means 700 as the previous device. Thedifference resides in the lifting means 500′ which comprises articulatedbearings 510 disposed between rail 310 and counter-rail 210. Whencounter-rail 210 is displaced in horizontal translation Th by ball andsocket 710 in contact with tie rod 750, it simultaneously effectsvertical translation Tv due to the pivoting of bearings 510 betweentheir fixed point, integral with rail 310, and their movable point,integral with counter-rail 210. FIGS. 9A and 9B show roller device 140in retracted and extended positions, respectively.

FIGS. 10A and 10B are schematic representations of a sixth roller device150 in which the actuation means 800 comprises an actuator in the formof a cylinder 810 integral with roller device 150 and associated with ablock formed of a tie rod 850 added to machine 20. Cylinder 810 is adouble cylinder, hydraulic or pneumatic, consisting of one chamber andtwo perpendicular pistons 820, 840. One piston 820 is essentiallyvertical and enters into contact with tie rod 850. It is associated witha recall spring 830. The other piston 840 is generally horizontal andattached to the front extremity of counter-rail 210. In FIG. 10A,cylinder 810 is at rest, which corresponds to counter-rail 210 being inthe lower position in which rollers 230 are retracted inside rail 310.This lower position is stable. In FIG. 10B cylinder 810 is actuated bytie rod 850 which exerts an upward vertical force on piston 820, causingit to rise by compressing its recall spring 830 and causing the fluid inits chamber to push piston 840 out, said piston 840 then exertinghorizontal force on counter-rail 210. Counter-rail 210 effectssimultaneously with its horizontal translation Th, vertical translationTv due to the displacement of rollers 240 along inclined ramps 331.Counter-rail 210 is moved to the upper position in which rollers 230project above surface S of rail 310. This upper position is not stablebecause when forks 10 are disengaged from machine 20, piston 820 againmoves down due to the action of its recall spring 230, allowingcounter-rail 210 to descend inclined ramps 331 due to gravity and returnto the lower position, while cylinder 810 is returned to the restingposition (cf. FIG. 10A).

FIGS. 11A and 11B are schematic representations of a seventh rollerdevice 160 similar to the preceding one, with the actuation means 900also comprising an actuator in the form of a cylinder 910 integral withroller device 150 and associated with a block formed of a tie rod 950added to machine 20. In this variation cylinder 910 is a doublecylinder, hydraulic or pneumatic, consisting of two pistons 920, 940,each associated with a separate chamber 911, 913, the two chambers beingjoined by a conduit 912. One of the pistons 920 is generally vertical inorder to enter into contact with tie rod 950. It is associated with arecall spring 930. The other piston 940 is generally horizontal andattached to the rear extremity of counter-rail 210. In this variationinclined ramps 331 are reversed in relation to those of FIGS. 10A and10B. The functioning of this roller device 160 is the same as thepreceding one and will not be repeated.

FIGS. 12A and 12B are schematic representations of an eighth rollerdevice 170 in which the actuation means 1000 comprises an actuator inthe form of a rotating element 1010 cooperating with an inclined ramp1020 integral with roller device 170 and associated with a block formedof a tie rod 1050 added to machine 20. Inclined ramp 1020 is provided inthe area of the front extremity of rail 310 and oriented in thedirection of inclined ramps 331 on rail 310. Rotating element 1010 isattached so as to be movable in rotation and in translation within rail310 and guided by its axle 1011 inside grooves 1021 provided in thelateral walls of rail 310 and extending generally parallel to inclinedramp 1020. It is formed of three coaxial rollers 1012, 1013, 1014 ofdifferent diameters and movable in rotation relative to one another: afirst roller 1010 designed to move along inclined ramp 1020, a secondroller 1013 designed to move along a vertical ramp 211 located at thefront of counter-rail 210, and a third roller 1014 designed to movealong the horizontal plane of tie rod 1050. In FIG. 12A, roller device170 is at rest, corresponding to counter-rail 210 being in the lowerposition in which rollers 230 are retracted inside rail 310. This lowerposition is stable. In FIG. 12B rotating element 1010 is actuated by tierod 1050 which exerts an upward vertical force on it using its thirdroller 1014, causing it to move up by moving along inclined ramp 1020using its first roller 1012 and simultaneously on vertical ramp 211 ofcounter-rail 210 using its second roller 1013 and then exertinghorizontal force on counter-rail 210. Counter-rail 210 effectssimultaneously with horizontal translation Th, vertical translation Tvdue to the displacement of rollers 240 along inclined ramps 331.Counter-rail 210 is moved to the upper position in which rollers 230project above surface S of rail 310. This upper position is not stablebecause when forks 10 are disengaged from machine 20, rotating element1010 redescends due to gravity along inclined ramp 1020, whilecounter-rail 210 simultaneously descends inclined ramps 331 due togravity to return to the lower position, with roller device 170 beingreturned to the resting position (cf. FIG. 12A).

FIGS. 13A and 13B are schematic representations of a ninth roller device180 similar to the preceding one, with the actuating means 1100 alsocomprising an actuator in the form of a rotating element 1110cooperating with an inclined ramp 1120 integral with roller device 180and associated with a block formed of a tie rod 1150 added to machine20. In this variation inclined ramp 1120 is provided at the frontextremity of counter-rail 210 and oriented in the opposite directionfrom inclined ramps 331 on rail 310. Rotating element 1110 is attachedto be movable in rotation and in translation inside rail 310 and guidedby its axle 1111 in groves 1121 provided in the lateral walls of rail310 and extending generally vertically. It is formed of three coaxialrollers 1112, 1113, 1114 of different diameters and movable in rotationrelative to one another: a first roller 1112 designed to move along avertical ramp 311 provided in the zone of the front extremity of rail310, a second roller 1113 designed to move along inclined ramp 1120 ofcounter-rail 210, and a third roller 1114 designed to contact thehorizontal plane of tie rod 1150. This third roller 1114 may be anon-rotating one, since its displacement is limited to verticaltranslation. The operation of this roller device 180 is similar to thepreceding device 170.

It is clearly apparent that the roller device according to the inventionoriginates from a simple kinematic concept. For this reason it iseconomical to buy as well as to maintain; it occupies a small amount ofspace and it is durable. More specifically, counter-rail 210 can beeasily removed from rail 310 to facilitate cleaning and maintenance.Because the actuator is integral with rail 310, it does not interferewith the performance of the load handling device. The advantage of thisactuator is that it is automatically and mechanically activated by ablock while the forks are being attached to the machine, without anyenergy input.

The roller device as described can be sold with forks to retrofitload-handling apparatuses already in use, or integrated into newequipment. It is for this reason that the invention also applies toload-handling apparatuses (not shown) equipped with such a rollerdevice.

The present invention is not limited to the exemplary embodimentsdescribed, but extends to any modification and variation obvious to aperson skilled in the art while still remaining within the scope ofprotection defined by the attached claims.

1-21. (canceled)
 22. A roller device (100-180) for displacing a load (1)in a generally horizontal plane between a load handling apparatus withforks and a machine (20), the device being designed to equip the forks(10) of a handling device, the roller device comprising; at least onerail (310) defining at least one plane contact surface (S) capable ofsupporting the load (1) when the load is static, the rail (310) beinghollow, generally horizontal, and provided with a longitudinal opening(320); at least one counter-rail (210) housed inside the rail (310) andinside of which roller elements (230) are attached opposite thelongitudinal opening (320), the roller elements (230) being located in aplane that is generally parallel to the surface (S) and capable ofsupporting the load (1) when the load is moving; and an actuating means(400, 400′, 600-1000) being connected to at least one of the rail (310)and the counter-rail (210) so as to be movable relative to another ofthe rail (310) and the counter-rail (210) between at least one lowerposition and one upper position, in the upper and the lower positions,the load is supported either by the rail (310) or by the counter-rail(210), the actuating means being disposed to displace the at least onerail (210) and the at least one counter rail (310) in at least ahorizontal translation (Th), with lifting means (500, 500′) beingdisposed between the at least one rail (210) and the at least onecounter rail (310) to cause the at least one rail (210) and the at leastone counter rail (310) to move in a vertical displacement (Tv)simultaneously with the horizontal displacement (Th), the actuatingmeans (400, 400′, 610-1100) comprises, at least one block (450, 20′,650-1150) designed to be attached to the machine (20), and at least oneactuator (410, 410′, 610-1110) disposed between the at least one rail(210) and the at least one counter rail (310) and designed to cooperatewith the block and to transform a vertical force exerted by the block onthe actuator into a horizontal force exerted by the actuator on the atleast one rail (210) and the at least one counter rail (310) to displacethe load in the horizontal translation (Th) when the forks (10) on theload handling apparatus are connected to the machine (20).
 23. Theroller device (100-130, 150-180) according to claim 22, wherein thelifting means (500) comprises inclined ramps (331) integral with therail (310) and designed to cooperate with the roller elements (230) onthe counter-rail (210).
 24. The roller device according to claim 23,wherein the inclined ramps (331) define at least a first zone (331 a)designed to allow at least tops of the roller elements (230) to project,a second zone (331 b) designed to cover the roller elements (230), andan intermediate zone (331 c) forming, in combination with the rollerelements, the lifting ramps.
 25. The roller device according to claim24, wherein each of the roller elements comprise at least one roller(230) designed to support the load (1) in a moving position, the roller(230) being attached to a generally horizontal axle (220) between twoother rollers (240) of smaller diameter, the two other rollers (240)being in contact with the inclined ramps (331).
 26. The roller device(140) according to claim 22, wherein the lifting means (500′) comprisesarticulated bearings (510) having a first extremity connected to therail (310) and a second extremity connected to the counter-rail (210).27. The roller device according to claim 22, wherein the actuator ischosen from a group comprising at least a pivoting lever (410, 410′), aball and socket (710), a rotating element (610), and a cylinder (810,910).
 28. The roller device according to claim 22, wherein the rail(310) is fixed and the counter-rail (210) supporting the roller elements(230) is movable and cooperates with the actuator (410, 410′, 610-1110),the actuator being designed to displace the counter-rail (210) from thelower position to the upper position when in contact with the block(450, 20′, 650-1150) and to allow the counter-rail (210) to descend intothe lower position by gravity when the counter-rail (210) is no longerin contact with the block.
 29. The roller device (100) according toclaim 28, wherein the actuator comprises at least one pivoting lever(410) attached to the rail (310) by an axle (420) oriented in agenerally perpendicular direction to a direction of the horizontaldisplacement (Th) of the counter-rail (210), the pivoting lever (410)comprising at least two contact zones (430, 440) located on either sideof the axle (420), a first contact zone (440) is in contact with thecounter-rail (210) and a second contact zone (430) is designed tocooperate with the block (450).
 30. The roller device according to claim29, wherein the pivoting lever (410) comprises at least a first rollerelement (230) located between the two contact zones (430, 440) anddesigned to complement the roller elements (230) on the counter-rail(210) when the counter-rail (210) is in the upper position.
 31. Theroller device (110) according to claim 28, wherein the actuatorcomprises at least one pivoting lever (410′) attached to thecounter-rail (210) by an axle (420′) oriented in a generallyperpendicular direction to a direction of horizontal displacement (Th)by the counter-rail (210), the pivoting lever (410) comprising at leasttwo contact zones (430′, 440′), a first contact zone (440′) is incontact with the rail (310) and a second contact zone (430′) is designedto cooperate with the block
 32. The roller device according to claim 31,wherein the first contact zone (440′) consists of a travel ramp capableof cooperating with a rotating element (441′) integral with the rail(310).
 33. The roller device (120) according to claim 28, wherein theactuator comprises at least one rotating element (610) attached to thecounter-rail (210) by an axle oriented in a generally perpendiculardirection to a direction of horizontal displacement (Th) of thecounter-rail, the rotating element (610) being designed to move along aninclined ramp (620) integrated within the block (650), the rail (310)being guided in vertical translation within the block (650) by a tenon(630) and a slide (640) system.
 34. The roller device (130, 140)according to claim 28, wherein the actuator comprises at least one balland socket (710) having at least one contact zone (720) disposed at anintersection of two articulated lever arms (730) respectively connectedto the rail (310) and to the counter-rail (210) along axles that aregenerally perpendicular to the horizontal displacement (Th) of thecounter-rail (210), the contact zone (720) being designed to cooperatewith the block (750).
 35. The roller device according to claim 29,wherein the contact zones (430, 440, 430′, 720) are comprised ofrotating elements.
 36. The roller device (150, 160) according to claim28, wherein the actuator comprises at least one double cylinder (810,910), a first piston (840, 940) of which cooperates with thecounter-rail (210) and is generally parallel to the horizontaldisplacement (Th), and a second piston (820, 920) of which is designedto cooperate with the block (850, 950) and is generally perpendicularrelative to the first piston (840, 940).
 37. The roller device accordingto claim 36, wherein the second piston (820, 920) is associated with arecall means (830, 930).
 38. The roller device (160) according to claim36, wherein chambers (911, 913) of the first and the second pistons(920, 940) are separate and interconnected by at least one conduit (912)housed in the rail (310).
 39. The roller device (170, 180) according toclaim 28, wherein the actuator comprises at least one rotating element(1010, 1110) attached to the rail (310) by an axle (1011, 1111) orientedgenerally perpendicular to the horizontal displacement (Th) of thecounter-rail (210) and guided in translation within the rail (310) bygrooves (1021, 1121), the rotating element (1010, 1110) being designedto cooperate with two ramps (1020, 211; 311, 1120) provided on the rail(310) and the counter-rail (210), respectively, at least one of theramps (1020, 1120) being inclined.
 40. The roller device according toclaim 39, wherein the rotating element (1010, 1110) comprises at leastthree coaxial rollers (1012, 1013, 1014; 1112, 1113, 1114) of differentdiameters, at least two of the three coaxial rollers are movable inrelation to each other, the two of the three coaxial rollers beingdesigned to respectively cooperate with the ramp (1021, 311) integralwith the rail (310), the ramp (211, 1120) integral with the counter-rail(210), and the block (1050, 1150).
 41. The roller device according toclaim 22, wherein the block is selected from among at least a tie rod(450, 650-1150) capable of receiving a front extremity of the forks (10)and a machine table (10′), and is at least partially shaped to becompatible with the actuator (410, 410′, 610-1110).
 42. A load handlingdevice with forks for displacing a load (1) in a generally horizontalplane between the load handling device and a machine (20), the forks(10) comprise the roller device (100-180), the device being designed toequip the forks (10) of a handling device, the roller device comprising;at least one rail (310) defining at least one plane contact surface (S)capable of supporting the load (1) when the load is static, the rail(310) being hollow, generally horizontal, and provided with alongitudinal opening (320); at least one counter-rail (210) housedinside the rail (310) and inside of which roller elements (230) areattached opposite the longitudinal opening (320), the roller elements(230) being located in a plane that is generally parallel to the surface(S) and capable of supporting the load (1) when the load is moving; andan actuating means (400, 400′, 600-1000) being connected to at least oneof the rail (310) and the counter-rail (210) so as to be movablerelative to another of the rail (310) and the counter-rail (210) betweenat least one lower position and one upper position, in the upper and thelower positions, the load is supported either by the rail (310) or bythe counter-rail (210), the actuating means being disposed to displacethe at least one rail (210) and the at least one counter rail (310) inat least a horizontal translation (Th), with lifting means (500, 500′)being disposed between the at least one rail (210) and the at least onecounter rail (310) to cause the at least one rail (210) and the at leastone counter rail (310) to move in a vertical displacement (Tv)simultaneously with the horizontal displacement (Th), the actuatingmeans (400, 400′, 610-1100) comprises, at least one block (450, 20′,650-1150) designed to be attached to the machine (20), and at least oneactuator (410, 410′, 610-1110) disposed between the at least one rail(210) and the at least one counter rail (310) and designed to cooperatewith the block and to transform a vertical force exerted by the block onthe actuator into a horizontal force exerted by the actuator on the atleast one rail (210) and the at least one counter rail (310) to displacethe load in the horizontal translation (Th) when the forks (10) on theload handling apparatus are connected to the machine (20).